It has never been clear whether Scarface was actually just an aspect of Wesker’s Multiple Personality Disorder, or if he had actually somehow gained sentience. There have been several instances where Scarface has functioned independently of a human controller, but this may also be a reflection of the controller's mental state at the given moment. On occasion, Scarface has been animate during times when Wesker was asleep or unconscious, or not even present at all. One of the strongest arguments for suggesting that Scarface may be a separate consciousness is the fact that he always maintains the same personality no matter who is operating him

I could be wrong, because I haven't read the full issue, but the big difference is that the new broad likes being a homicidal maniac, where Wesker was always at odds with it. I know some people hated him and thought it was a terribly cheesy concept (and in some ways it certainly was, no argument), but I found it a fascinating personality split that not even Two-Face could achieve as a character.